1. Field of the Invention
The present invention relates to the field of digital communications. More particularly, the present invention relates to a digital communication system and method for efficiently transferring digital information between multiple terminals over a single channel communication link.
2. Background Art Related to the Invention
In anticipation of the increased need to transmit digital information rapidly across a substantial distance, the telephone industry has developed a digital communication link which enables a twisted pair of copper lines to transfer a substantial amount of digital information from one terminal to another with only minimal modification of prior installed telephone hardware. This digital communication link is referred to as an Integrated Services Digital Network (xe2x80x9cISDNxe2x80x9d) which is well known in the art and defined by International Telegraph and Telephone Consultative Committee (xe2x80x9cCCITTxe2x80x9d). In recent years, the telephone industry has begun to utilize a sub-category of ISDN; namely, a Narrow-band Integrated Services Digital Network (xe2x80x9cN-ISDNxe2x80x9d) which partitions data into several channels. A further sub-category, well-known but still in development, is a Broad-band ISDN (xe2x80x9cB-ISDNxe2x80x9d) which partitions data into even more channels than N-ISDN.
Referring to FIG. 1, a conventional N-ISDN system 100 generally is configured with a terminal coupled at one end of a dedicated ISDN communication link and a remote terminal coupled to the other end of the ISDN communication link. A xe2x80x9cterminalxe2x80x9d represents either a device (e.g., a computer, facsimile machine, digital telephone, etc.) which produces at least one digital data stream at sixty-four (64) kilobits per second (xe2x80x9cISDN terminalxe2x80x9d) or a xe2x80x9cnon-ISDN terminalxe2x80x9d being any other device with a serial RS-232 port. As shown, a non-ISDN terminal 105, more specifically its serial port 110, is coupled to a terminal adapter 115 through a coaxial cable line 120. The terminal adapter 115 enables older generation terminals to be compatible with ISDN protocols. It is contemplated that the terminal adapter 115 may be employed within the terminal 105 or externally as shown.
The terminal adapter 115 is coupled to an interface connector 125 through a bi-directional digital line 126. The interface connector 125 is coupled between the bi-directional digital line 126 and a corresponding dedicated, pre-configured ISDN communication link 130. If the ISDN communication link 130 is a N-ISDN communication link, the interface connector 125 is configured as a xe2x80x9cbasic rate interfacexe2x80x9d being well known in the art for supporting digital transmissions of up to 192 kilobits per second (xe2x80x9ckb/sxe2x80x9d) with framing bits. A typical embodiment of the basic rate interface provides two bi-directional, sixty-four (64) kb/s information channels and one bi-directional sixteen (16) kb/s control channel. In addition to these three channels, other supplemental channels may be available, for example, a twelve (12) kb/s channel for framing/timing and a four (4) kb/s channel for overhead to support network operations. It is further contemplated that the interface connector 125 may be configured as a xe2x80x9cprimary rate interfacexe2x80x9d if the ISDN communication link 130 is a B-ISDN communication link.
The ISDN communication link 130 is coupled to a second terminal adapter 135 remotely located from the terminal 105. The second terminal adapter 135 also is coupled to a remote terminal 140. As a result, the conventional N-ISDN system enables the terminal 105 to transmit information to and receive information from the remote terminal 140. However, there are several disadvantages associated with this conventional ISDN system.
One disadvantage is that conventional ISDN systems do not efficiently utilize available bandwidth. For example, bit streams containing information crucial in maintaining acceptable communications between terminals are not given greater priority than other transmissions. Another example is that conventional ISDN systems utilize two fixed bandwidth channels to support digital transmissions. In the event that a specific terminal is not using a substantial portion of bandwidth provided in one or both of these channels, a likely situation since different amounts of bandwidth may be required for different compression needs, certain transmissions and/or operations may be delayed or precluded.
Yet another disadvantage is that multiple ISDN communication links and interface connectors are required to support multiple terminals. The additional costs associated with these connectors and ISDN communication links effect the general affordability of the conventional ISDN system.
Hence, it is desirable to provide a method and apparatus for supporting communications through a single connector over a single channel communication link (preferably an ISDN link) in order to reduce additional costs associated with multiple interface connectors. It is further desirable to configure the apparatus and method to efficiently allocate available bandwidth of the ISDN communication link to support real-time, interactive communications.
A method and apparatus for providing digital information in a multiple interactive environment over a single communication link is described. Information, such as audio, control data and video, is generated by at least one terminal and is transmitted from the terminal to a resource allocation device. The resource allocation device (i) determines what portion of that information will be transmitted over the communication link, (ii) constructs information packets according to the allocated bandwidth and (iii) controls the multiplexing of the information packets.